It is known that the most efficient and at the same time the most economical method for the recycling of biomasses consists of aerobic biodegradation by microorganisms to produce fertilizers used in agriculture.
Common to all proven methods and equipment is the necessity to aerate the biomass for the purpose of promoting the growth of aerobic bacterial flora at a level which is sufficient to cause biodegradation in relatively short periods of time and without giving off undesirable odors, a side effect of the decaying process.
Aside from the amount of air which is necessary for the process and the advisability of the suction and blowing of said air, no known system is capable of guaranteeing what is fundamental, i.e., an even distribution of air throughout the mass and a constancy over time, since, at present, after short periods of time, the aeration system becomes clogged and the process of biodegradation stops and cannot be re-activated due to the presence of a considerable mass of material which, especially in automatic systems, cannot be removed.
The normally used aeration installations are placed on the bottom or the floor of the digesting installation and can be grouped into two basic systems.
The first of these systems is comprised of a collector located beside the reservoir, through which air is taken in or blown out, and which is connected to a network of conduits which pass through the reservoir. Each conduit is endowed with openings or nozzles through which the air is introduced into or suctioned from the mass. Each conduit is equipped with a valve which serves to control the air flow.
The second system is comprised of small transverse channels placed in the reservoir floor, which are covered with slit tiles to allow the passage of air while preventing the passage of material. These small transverse channels are interconnected by a small longitudinal channel which is provided to allow the periodic washing of all of the small channels with the passage of water to a collection chamber.
Both of these basic systems present notable inconveniences, the essential of which include:
a) The consistency and air permeability of the biological mass being treated vary from point to point. Indeed, in a continuous process digesting installation, which is the type utilized for medium and high production, one finds fresh material, material which is in the maturing state and material which has already matured, and each of these materials has a different degree of air permeability, and thus the air passing through a conduit will tend to exit (or enter) from the openings at which it meets the least resistance due to the different states of the material. The same can be said with respect to the small channel system with the additional drawback that it is impossible to interpose control valves.
b) The biological mass must always be very moist (with water content greater than 50%) so that the bacterial flora can develop. As such, an appreciable amount of drainage occurs towards the lower layers, which tend to become compacted on the bottom of the digesting installation, creating a layer which is impermeable or having a low degree of permeability, which cannot be removed using mechanical stirring means, which, for obvious reasons, must pass at a certain distance, however minimal, from the bottom. This bottom layer, which gradually becomes impermeable, generally forms a few months after the activation of the installation and is reinforced by the presence of colloidal substances which are formed during the process. This problem normally clogs the installation and, in the present state, requires the emptying of the reservoir and the cleaning of its floor. Such an operation, however, is inconceivable in continuous cycle industrial installations which, once filled, should never be emptied, given that the biological process which is occurring therein requires a long period of time to begin.
An object of this invention is a device which is capable of guaranteeing with certainty the passage of air through the mass which is being treated, in a uniform and continuous manner, while preventing the process of oxidation from being reduced over time.
Another object of the invention is the provision of the means to unblock, even automatically, the air outlets, which can become clogged.